Steel alloy



UNITED STATES CHARLES MORRIS JOHNSON, OF AVALON, PENNSYLVANIA.

STEEL ALLOY.

saaaii.

No Drawing.

or discovered a certain new and useful Improvement in Steel Alloys, of which improvement the following is a specification.

My invention isof an alloy steel of great hardness. While not limited in applicability to any particular field, it finds important use in the manufacture of armorplate, and particularly of gun-shields. I

have found, for example, that, comparing my steel with the best steels heretofore available for the purpose, a gun-shield, if made of my steel, may, without loss in resistance to permeability be reduced in thickness from .500 of an inch to .362. In these days, in the field of aeronautics, most exacting demands have arisen; if, with no loss in resistance to penetration, the thickness (and weight) of the armor of a battle aeroplane may be reduced twenty-five per cent., or even by a much smaller subtrahend, the gain is a notable one. As I have already said, my invention is not limited in applicability to material for aeroplanes, nor even to the wider field of munitions of war, but the aeroplane service affords an emphatic instance of the new results I attain.

My alloy steel belongs to that class or family of alloys definable as silicon-nickelsteels, of which the essential components are the metals named in the definition, and my invention consists in adding to the essential components two others: namely, chromium and vanadium. Mine is a chromium-vanadium-silicon-nickel steel, of the composition which I am about to state. In respect to its carbon and manganese contents, these are its characteristics: Ihe carbon is very low, preferably under .6 of one per cent.; the manganese content must necessarily be low, but will preferably be as great as shearing conditions permit. cent. I have found to be a good workable proportion, but under existing conditions it may hardly exceed one per cent. Silicon may be present in quantity as great as 2.50 per cent., but, if kept as low as 1 per cent. best results are attained.

The composition of my steel as revealed by analysis is, exclusive of the iron content, as follows:

Carbon .30 to .60 of one per cent.

Specification of Letters Patent.

.70 to .80 of one per Patented June 8, 1920.

Application filed August 7, 1919. Serial No. 315,809.

Manganese, not more than one per cent. Silicon 1.00 or less to 2.50 percent. Chromium .30 to .80 of one per cent.

' Vanadium .10 to .30 of one per cent.

Nickel 1.50 to 3.50 per cent. 7 7 Such being the range within which my invention may be enjoyed, my preferred analysis is this:

Carbon .35 to .45 of one per cent.

Manganese .70 to .80 of one per cent.

Silicon 1.00 per cent.

Chromium .50 to .60 of one per cent.

Vanadium .15 to .25 of one per cent.

Nickel 3.00 to 3.25 per cent.

But for the difiiculties of manufacture, I should prefer to increase the percentages of chromium, vanadium, and nickel.

The steel of my invention may conveniently be melted in an open-hearth furnace, following the ordinary methods of basic open-hearth treatment. The product, after casting, should be finished in slabs in the blooming mill, and then rolled to plates, ac-

cording to usual methods.

It is useful to speak of this detail of metallurgical art as a building of alloys. I

The old silicon-nickel-steel alloy is, so to speak, the foundation on which I build. I have added another story to the buildinganother tier to the pyramid. And my enlarged structure is a proper base for further building. I find that, upon the'structure which I have thus far defined, a chromium-vanadium-silicon-nickel alloying structure, I may superpose tungsten, for example, or tungsten and molybdenum together. I find that by adding 1.25 to 1.50% tungsten and an equal amount of molybdenum (silicon being 2.00 to 2.25%) I may reduce the thickness of the plate to .34 of an inch and have resistance to penetration still equal to a plate .50 of an inch thick, made of the best steel heretofore available, and I find that if in addition-I reduce the silicon content to 1%, a plate .32 of an inch will afford the same resistance to penetration.

I claim as my invention:

1. An alloy steel containing the following non-ferrous constituents in the proportions given: carbon, to .60 of one per gent; manganese, not more than .80 of one per cent.; silicon, 1.00 to 2.50%; chromium' .30 to .80 of one per cent.; vanadium .10 to .30 of one per cent.; nickel, 1.50 to 3.50%.

2. An alloy steel containing the following mium, .30 to .80 of one per cent.; vanadium .10 to .30 of one per cent.; nickel, 1.50 to 3.50%; tungsten 1.25 to 1.50%; molybdenum, 1.25 to 1.50%.

In testimony whereof I have hereunto set my hand.

CHARLES MORRIS JOHNSON: Witnesses ALICE A. TRILL, FRANCIS J. TOMASSON. 

